A quick,I hope, oscilloscope question!

[Larry4911]

OK, just received a lab-volt AE 793G the same as leader LBO-522?
Off ebay for £42.
I've only ever used an oscilloscope in a college lab, and only for Hz and TTL so need some advice.
Injected RF at 20Mhz cos it's a 20 Mhz oscilloscope.
At the lowest time devision of 0.2µs and the times 5 out. I'm getting 8 peaks of a sine wave on the screen.
Is it because A) my RF genny is in need of tune.
B) The scope is up the pictures
Or C) that's what it's supposed to read.
Any ideas please?

Thanks

Larry

 

[ericgibbs]

hi Larry,

Assuming your scope has 5 X divisions across the screen.
Set at 0.2µS/div with the Xmulti set a *1,the X sweep would be 1µSec.

With the Xmult at *5 the sweep would be 0.2µSec

The period of a 20MHz sine wave is 0.05µSec.

So would expect to see 4 positive half cycle peaks. ie 4 cycles.

If it was mult *10 it would be 8 cycles

EDIT:
In line with on1aag, IF you have 10 X divisions marked on the scopes graticule, it OK, IF only 5 X divs then its wrong.

How many marked X divisions are there on the graticule .??

 

[on1aag]

Hi Larry,

200nS and the 5x multiplier depressed gives you 40 nS/div.
10 horizontal divisions are 400 nS.
The period of a 20 MHz signal is 50 nS.
There will be eight periods on the screen.
Looks fine to me.

on1aag.

 

[Larry4911]

Ok, so that's two differing opinions. Any more?

Oh yes, and have you watched music on a scope. It's wild insn't it

Yes, ten.

Larry

 

[Larry4911]

I'm watching Gemeni FM on my new/old scope. First time I've ever watched radio. It's great.

Larry

 

[ericgibbs]

Ok, so that's two differing opinions. Any more?

Oh yes, and have you watched music on a scope. It's wild insn't it

Yes, ten.

Larry

hi,
Not two different opinions, different answers, either could be correct.

Some scopes have 5 X divs on the graticule others have 10 X divs.

In your case you have 10, so the display is correct.

Yes, we all go thru watching audio on the scope, try watching the video signal on your TV' s A/V socket.

Connect a mike to the scope and watch your own voice.

 

[Larry4911]

Yes, we all go thru watching audio on the scope, try watching the video signal on your TV' s A/V socket.

What frequancy for video? This only goes to 20Mhz.
Oh, yeh! And this scope has TV-H and TV-V.
Will that make a difference on video out or is that just for TV internal signals?

Thanks for all your help btw.

Larry

 

[ericgibbs]

Yes, we all go thru watching audio on the scope, try watching the video signal on your TV' s A/V socket.

What frequancy for video? This only goes to 20Mhz.
Oh, yeh! And this scope has TV-H and TV-V.
Will that make a difference on video out or is that just for TV internal signals?

Thanks for all your help btw.

Larry

hi,
What frequency do you think the A/V signal is operating at..? not 20MHz.

The TV-H and TV-V are for for scope sync, from the TV Horizontal or Vertical sync.

 

[Larry4911]

Thanks for that Eric.
Right, next thing on the shopping list - Waveform monitor. No, only kidding.

Damn, that is one hell of a complex waveform isn't it?

Larry

 

[Larry4911]

But the TV-H and V helped me to understand the signal better. They are in fact used to pick out the horizontal and vertical sync bits of the composite signal.

Thanks again.

Larry

 

[Muhammad89]

Thanks for that Eric.
Right, next thing on the shopping list - Waveform monitor. No, only kidding.

Damn, that is one hell of a complex waveform isn't it?

Larry

Waveform Monitor????
That really sounds interesting! I will try to get sum info on this
Muhammad89

 

[Muhammad89]

But the TV-H and V helped me to understand the signal better. They are in fact used to pick out the horizontal and vertical sync bits of the composite signal.

Thanks again.

Larry

I succeeded to find sum infrmation about the Waveform monitor and it is posted in here

Muhammad89

 

[ericgibbs]

But the TV-H and V helped me to understand the signal better. They are in fact used to pick out the horizontal and vertical sync bits of the composite signal.

Thanks again.

Larry

hi Larry,
Its a good idea to try to display different types of waveforms, it will help you understand and get the best from your scope.

Manuals are helpful, but there is nothing like 'hands on' experience when using a scope.

ALWAYS stay within the scopes input voltage ranges.!!!!
Dont fool around with trying mains inputs to the scope amps.

You have checked the X scan calibration, I would also check the Y calibration, some scopes have a 'ref square wave'.

Get decent probes for the scope *1 and *10 attenuation.

Happy scoping..